Math problem: Who is correct, The Teacher or The Student?

[HamburgerBoy]

Truth is as I stated before the question really lacks details so either answer could be right.

Question lacks the details required to make assumptions from it. Make assumptions from it.

 

[classy]

Tomorrow though I will ask a guy from work what he thinks is the answer. He has an MBA in mathematics. I will truthfully post what he says.

 

[HamburgerBoy]

Tomorrow though I will ask a guy from work what he thinks is the answer. He has an MBA in mathematics. I will truthfully post what he says.

Yes, a group of (mostly) rational adults on an internet forum are clearly not capable of reasoning out ~2nd grade mathematics without deferring to authority.

 

[silverpig]

Tomorrow though I will ask a guy from work what he thinks is the answer. He has an MBA in mathematics. I will truthfully post what he says.

An MBA is a business degree (Master of Business Administration).

This isn't a graduate level math problem.

 

[PlasmaBomb]

Tell me about it. It's pretty obvious this is a badly written problem. If you use the picture as a reference to change the basis to "1 cut in 10 minutes and 2 cuts would get you 3 pieces" then 20 is an obvious answer.

But if you need two cuts to make two pieces (say you have a 20 meter long stick and you're trying to make 1 meter pieces), then it's 15.

You are as bad as the teacher. If your first cut gives you a 1m and 19m piece, and the next cut gives you 2x 1m pieces and an 18m piece, why does the second cut take half the time???

 

[PlasmaBomb]

Teacher probably meant to be a ratio problem. (10 min)/(2 cuts) = (x min)/(3 cuts), so x = 15. It'd work that way if the problem wasn't about cutting boards.

That's the point, your equations are wrong! Math fail.

(10 min)/(1 cut) = (x min)/(2 cuts) is correct.

1 cut gives you two pieces, and 2 cuts gives you three. It really is that basic, and that is where the teacher has gone wrong.

 

[classy]

An MBA is a business degree (Master of Business Administration).

This isn't a graduate level math problem.

That's interesting. You assume this teacher doesn't have an MBA. All of us, me included who initially said twenty minutes have made that conclusion based on the picture. There are no dimensions mentioned. So in my inquiry to him, he has seriously delved into mathematic questions I know for sure. I am not knocking your mba in business, but I would like to get his take on the question.

Its not about the geniuses or retards, its a fun question I think. And honestly without seeing the rest of the test we really don't know if the picture was to be taken literally or not.

 

[Jaepheth]

ITT: Why you always show your work/reasoning on a math problem.

 

[PlasmaBomb]

Tomorrow though I will ask a guy from work what he thinks is the answer. He has an MBA in mathematics. I will truthfully post what he says.

An MBA is a business degree (Master of Business Administration).

This isn't a graduate level math problem.

That's interesting. You assume this teacher doesn't have an MBA. All of us, me included who initially said twenty minutes have made that conclusion based on the picture. There are no dimensions mentioned. So in my inquiry to him, he has seriously delved into mathematic questions I know for sure. I am not knocking your mba in business, but I would like to get his take on the question.

Its not about the geniuses or retards, its a fun question I think. And honestly without seeing the rest of the test we really don't know if the picture was to be taken literally or not.

Comprehension fail.

 

[PlasmaBomb]

ITT: Why you always show your work/reasoning on a math problem.

1 cut gives you two pieces, and 2 cuts gives you three.
Let x = 1 cut

x = 10 minutes
2x = 2(10)
2x = 20 minutes

It's so simple writing the workings is painful... it's not even a simultaneous equation...

Let x = time required
(10 min)/(1 cut) = (x min)/(2 cuts)
x = 10*2 = 20 minutes.

 

[Ben90]

Forget about the actual excercise....

If I take something and cut it into two parts and it takes X amount of time. Then if I take one of those two parts, it is half the size of the original. So in order to cut one of those parts in half again, it should in theory take me half the time because it is half the size it was orignally. Which would leave me with 3 parts.

Removing the physical exercise and looking only at the mathematics it would take me 15 minutes.

 

[HamburgerBoy]

btw, the teacher is wrong even if we are talking about a board being cut along the shorter dimension each time. First cut = 10 minutes. Next cut = 5 more minutes. Third cut = 2.5 minutes. Sum = 17.5. How did the teacher get 20 minutes for 4 pieces? Some of you guys seriously lack basic reasoning skills.

EDIT: I am a part of some of those guys. My apologies.

 

[PlasmaBomb]

btw, the teacher is wrong even if we are talking about a board being cut along the shorter dimension each time. First cut = 10 minutes. Next cut = 5 more minutes. Third cut = 2.5 minutes. Sum = 17.5. How did the teacher get 20 minutes for 4 pieces? Some of you guys seriously lack basic reasoning skills.

Check out the graph in the post above your.


lulz.

 

[HamburgerBoy]

Check out the graph in the post above your.

lulz.

But more esteemed members of this thread have made the same fallacy. :\

 

[classy]

btw, the teacher is wrong even if we are talking about a board being cut along the shorter dimension each time. First cut = 10 minutes. Next cut = 5 more minutes. Third cut = 2.5 minutes. Sum = 17.5. How did the teacher get 20 minutes for 4 pieces? Some of you guys seriously lack basic reasoning skills.

LOL

Where did you go to school.

I have 12x12 board. It takes me ten minutes to cut the board in half. I now have two 6x12 boards. 6 inches wide 12 inches long. I then cut the board in half width wise, which is 6 inches. To cut 12 inches took 10 minutes, now I have to cut 6 inches, which is half, so that takes me 5 minutes. Two cuts, 3 pieces = 15 minutes. Cut the other board now width wise 5 more minutes, 4 pieces, 3 cuts = 20 minutes.

 

[PlasmaBomb]

But more esteemed members of this thread have made the same fallacy. :\

As I posted earlier, the teacher and several of our esteemed members have fallen down here -

Teacher probably meant to be a ratio problem. (10 min)/(2 cuts) = (x min)/(3 cuts), so x = 15. It'd work that way if the problem wasn't about cutting boards.

Which is obviously wrong.

 

[PlasmaBomb]

LOL

Where did you go to school.

I have 12x12 board. It takes me ten minutes to cut the board in half. I now have two 6x12 boards. 6 inches wide 12 inches long. I then cut the board in half width wise, which is 6 inches. To cut 12 inches took 10 minutes, now I have to cut 6 inches, which is half, so that takes me 5 minutes. Two cuts, 3 pieces = 15 minutes. Cut the other board now width wise 5 more minutes, 4 pieces, 3 cuts = 20 minutes.

The question doesn't state that the pieces have to be the same size. The next cut in both cases is still 6" and would therefore be 20 minutes (10 + 5 + 5).

Plus the diagram shows a long thin board not a 12x12, so the evidence for using a square board is lacking... so I believe the point is moot.

 

[HamburgerBoy]

LOL

Where did you go to school.

I have 12x12 board. It takes me ten minutes to cut the board in half. I now have two 6x12 boards. 6 inches wide 12 inches long. I then cut the board in half width wise, which is 6 inches. To cut 12 inches took 10 minutes, now I have to cut 6 inches, which is half, so that takes me 5 minutes. Two cuts, 3 pieces = 15 minutes. Cut the other board now width wise 5 more minutes, 4 pieces, 3 cuts = 20 minutes.

Uh...

12x12 cutting for 10 minutes produces two 6x12 boards.

Cut one 6x12 board along the 6 and you now have one 6x12 board and two 3x12 boards (three boards total). Half the distance means half the time means an additional 5 minutes.

Cut the 3x12 board along the 3. This results in two 1.5x12 boards along with a 6x12 board and a 3x12 board (four boards total). Cutting it takes half as long as a 6x12 board, meaning an additional 2.5 minutes.

Add them up: 10 + 5 + 2.5 = 17.5. Unless I'm not understanding the dimensions (I mean, I do find it highly odd that everyone is talking about boards and rods as if they are two-dimensional), you're wrong.

 

[silverpig]

Uh...

12x12 cutting for 10 minutes produces two 6x12 boards.

Cut one 6x12 board along the 6 and you now have one 6x12 board and two 3x12 boards (three boards total). Half the distance means half the time means an additional 5 minutes.

Cut the 3x12 board along the 3. This results in two 1.5x12 boards along with a 6x12 board and a 3x12 board (four boards total). Cutting it takes half as long as a 6x12 board, meaning an additional 2.5 minutes.

Add them up: 10 + 5 + 2.5 = 17.5. Unless I'm not understanding the dimensions (I mean, I do find it highly odd that everyone is talking about boards and rods as if they are two-dimensional), you're wrong.

If you cut along the 6" side you will end up with two 6x6" squares, not two 3x12 boards.

 

[jman19]

Tomorrow though I will ask a guy from work what he thinks is the answer. He has an MBA in mathematics. I will truthfully post what he says.

You're clueless.

 

[thebomb]

Uh...

12x12 cutting for 10 minutes produces two 6x12 boards.

Cut one 6x12 board along the 6 and you now have one 6x12 board and two 3x12 boards (three boards total). Half the distance means half the time means an additional 5 minutes.

Cut the 3x12 board along the 3. This results in two 1.5x12 boards along with a 6x12 board and a 3x12 board (four boards total). Cutting it takes half as long as a 6x12 board, meaning an additional 2.5 minutes.

Add them up: 10 + 5 + 2.5 = 17.5. Unless I'm not understanding the dimensions (I mean, I do find it highly odd that everyone is talking about boards and rods as if they are two-dimensional), you're wrong.

To get 20 min total he cut the other 6x12 board not the 3x12 board as you have done.

This question is pretty straightforward and some of your are making it more complicated than it needs to be. If it took Marie 10 minutes to make 2 pieces then that means she can make 1 piece every 5 minutes. If three pieces are needed then the answer is 5 minutes per piece x 3 pieces = 15 minutes.

 

[classy]

Uh...

12x12 cutting for 10 minutes produces two 6x12 boards.

Cut one 6x12 board along the 6 and you now have one 6x12 board and two 3x12 boards (three boards total). Half the distance means half the time means an additional 5 minutes.

Cut the 3x12 board along the 3. This results in two 1.5x12 boards along with a 6x12 board and a 3x12 board (four boards total). Cutting it takes half as long as a 6x12 board, meaning an additional 2.5 minutes.

Add them up: 10 + 5 + 2.5 = 17.5. Unless I'm not understanding the dimensions (I mean, I do find it highly odd that everyone is talking about boards and rods as if they are two-dimensional), you're wrong.

What, lol. Are you serious, lol.

I have one 12 x 12 board

First cut produces two 6 x 12 boards.

Take one of those pieces and now my second cut split the board in two. But I will cut the length of the smaller plane, which is 6 inches

At the end I have one 6 x 12 and two 6 x 6.

If I slice the other board I will have four 6 x 6 pieces.

LOL, where you learn how cut, hehehehehehe.

But again this is all speculation because no dimensions were given. We assume the board is like in the picture, but obviously that was not the case. And if you apply this same formula to other case that don't involve board cutting, with a board like in the picture, then teacher is correct.

A lot assumptions.

 

[silverpig]

That's interesting. You assume this teacher doesn't have an MBA. All of us, me included who initially said twenty minutes have made that conclusion based on the picture. There are no dimensions mentioned. So in my inquiry to him, he has seriously delved into mathematic questions I know for sure. I am not knocking your mba in business, but I would like to get his take on the question.

Its not about the geniuses or retards, its a fun question I think. And honestly without seeing the rest of the test we really don't know if the picture was to be taken literally or not.

You can't have an MBA in math. The degree doesn't exist. You can have an M.Sc in math, or maybe an MA in math as some schools still have math in the arts department.

 

[DrPizza]

Nice try, but look at the picture.

It was a joke! The problem looks like an elementary level math problem. Elementary teachers are notoriously ill-prepared to teach mathematics. (So sayeth the National Council of Teachers of Mathematics.)

And for those who didn't pick up on the fact that it was a joke & are still coming up with counter-examples as to how 15 minutes would work, it didn't say the pieces had to be rectangular either. So, she could cut of a tiny piece on a corner in about 10 seconds. It's implied by such problems that the cuts are the same length. The teacher is just stupid, else too lazy to think. (i.e. if I had 3 students get a different answer than my answer key, I'd start questioning myself to see if I made a careless mistake; it happens sometimes. )

 

[classy]

You're clueless.

That might be true, but I know how to cut a flipping board.